Kaine: The Hill describes him as a centrist and "less risky" pick for Clinton, and a loyalist who can "reinforce" her argument only those with experience are ready to serve in the White House. He also was vetted by President Barack Obama as a potential running mate in 2008.

Warren: "Impressed" those who watched her enthusiastic appearance with Clinton in Ohio Monday, The Hill reports, but her anti-Wall Street and international trade deal rhetoric, "complicated" history with Clinton, and her own competitive "power base" work against her being Clinton's No. 2.

Brown: The liberal senator has advantages "similar to Warren’s in terms of revving up progressives" — and would come with a bonus: he's from a swing state, according to The Hill.

Perez: On Clinton's short list, according to The Wall Street Journal. But since Donald Trump "is doing so badly with minorities in polls … Clinton may simply feel no great need to choose a Hispanic running mate," according to The Hill.

Booker: Critics say he's too social media-centric, The Hill reports, but is "youthful and charismatic." The question is whether he could hold up under the spotlight of a presidential race, The Hill reports.

Klobuchar: Has political chops and is an enthusiastic Clinton backer; next to Warren, the most likely woman to be named a running mate, The Hill reports.

Becerra: He's a big supporter of immigration reform, but relatively unknown on the national stage, The Hill reports.

Warner: Similarities with fellow Virginian, Tim Kaine — but won his 2014 re-election in a squeaker, "which doesn't augur well for his chances," The Hill reports.

Franken: Best known for his days with NBC's "Saturday Night Live," and though interested in the job, may be an "unlikely choice given that Clinton's campaign is trying to portray Trump as unqualified and lacking gravitas," The Hill reports.

Sen. Elizabeth Warren's clashes with Donald Trump and enthusiastic campaign debut appearance with Hillary Clinton have vaulted the progressive into high-profile contention for the No. 2 spot on the Democratic ticket.